PCA systems typically include an electronic infuser unit which can be readily activated by a patient to enable the patient to directly administer an analgesic in a prescribed dosage and within a predetermined time period. The infuser unit accepts a vial having a desired analgesic sealed therein and an injector element which are activated by the infuser unit to dispense the analgesic in the prescribed dosage from the vial to a drug administration set in communication with the injector element.
The drug administration set typically includes an anti-siphon valve at one end that is manually connected to the injector element at the point of use. Other portions of the drug administration set are manually connected to an intravenous administration set and a venipuncture device for administration of the analgesic into the blood stream of the patient.
Such systems typically include a vial having an opening sealed by a stopper or plunger and a sealing cap which encloses the stopper within the vial to maintain the sterility of the plunger and vial before use. The injector element includes a metal cannula which extends between first and second opposite ends where the portion of the cannula proximate the first end pierces the stopper upon threaded engagement therewith. Both the first and second ends of the injector element also include sealing caps to prevent contamination of the cannula and reduce the risk of the cannula accidentally "sticking" an attendant before or during assembly.
FIG. 5 illustrates a prior art injector element having a sealing cap on its second end and positioned for threaded engagement with an anti-siphon valve of a drug administration set. The anti-siphon valve also includes a protective cap to reduce contamination of the anti-siphon valve and the microbore administration set before use.
In these existing PCA systems, both the vial and the injector element are provided in the same sterile package while the anti-siphon valve and drug administration set are provided in a separate sterile package. Accordingly, when a vial is emptied during use, the vial and injector element first are removed from the infuser unit, the injector element is manually disconnected from the anti-siphon valve and the empty valve and associated injector element are removed from the infuser unit and discarded as non-recyclable waste.
A new package containing a full vial and a new injector element then is retrieved from stock, the protective covers from the vial and both ends of the injector element are removed and the injector element is threadedly connected to the stopper of the vial. The anti-siphon valve then is threadedly connected to the injector element and the vial and injector element are connected to the infuser unit.
A disadvantage of these existing PCA systems is that the anti-siphon valve must be disconnected from the used injector element and re-attached to a new injector element each time the vial is emptied. This not only increases costs by having to provide a new injector element each time a vial is replaced, but also requires additional installation time. Such systems also increase the risk of contamination by breaking open the established sterile system as well as the risk of an accidental overdose by an improper connection.
Additionally, the risk of a needle stick to the patient or the attendant exists from handling the injector element while trying to connect the rather small anti-siphon valve to the injector element. This work typically is done at the bedside of a patient which sometimes does not afford ample room or proper lighting making the work difficult.
Furthermore, since the injector element includes a cannula, it cannot be recycled. Thus, replacement of an injector element each time the vial needs replaced substantially increases the quantity of non-recyclable waste.
Finally, since both the vial and injector element are replaced when the vial is empty, storage must be provided for both of these items. Storage areas in hospitals and other treatment centers is at a premium, especially for drugs which have additional security, refrigeration or other requirements, such as an analgesic, particularly a controlled substance such as morphine.
It therefore would be desirable to provide a one-piece injector assembly for use with a vial which preferably includes an anti-siphon valve permanently connected to both an injector element and a drug administration set. Such an injector assembly would enable an attendant to merely remove an empty vial from the injector element and install a full vial to the injector element without removing the anti-siphon valve or drug administration set from the injector element.
Since the anti-siphon valve does not need to be disconnected and re-attached to the injector element, costs and assembly time are significantly decreased which are major goals in the health care industry. Additionally, the risk of contamination and a needle stick is reduced since the only connection necessary is the relatively easy threaded connection between the vial stopper and the injector element.
Furthermore, since such an injector assembly does not require a new injector element each time the vial is replaced, the amount of non-recyclable waste is reduced by approximately 60% which provides a distinct environmental advantage. This similarly provides a reduction in the amount of storage space required for injector elements by approximately 60%.
Additionally, since the manual connection between the anti-siphon valve and the injector element is eliminated, the risk of improper connection or breaking of these elements is reduced, thereby reducing the possibility of an accidental overdose.
The present invention provides an injector assembly and method of installing the injector assembly to an infuser unit which can accommodate the above-discussed benefits and features.